Wide viewing angle polarizer and liquid-crystal display device

ABSTRACT

A wide viewing angle polarizer having: a polarizing film; and a phase retarder adhesively laminated on at least one surface of the polarizing film through an adhesive layer, the phase retarder being made of a composite phase retarder constituted by a laminate in which a retardation layer B of a cholesteric liquid crystal-oriented solidified layer in a selective reflection wavelength range of not larger than 350 nm is supported by a retardation layer A of a thermoplastic resin exhibiting positive birefringence, the composite phase retarder being formed so that the laminate has Re of not smaller than 10 nm and Rth−Re of not smaller than 50 nm when Re and Rth are defined as Re=(nx−ny)X d and Rth=(nx−nz)X d respectively in which nx and ny are in-plane main refractive indices, nz is a thicknesswise refractive index, and d is a layer thickness. A liquid-crystal display device having: a liquid-crystal cell; and a wide viewing angle polarizer defined above and disposed on at least one surface of the liquid-crystal cell.

The present application is based on Japanese Patent Application No.2001-312162, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wide viewing angle polarizer adaptedfor improvement in viewing angle characteristic of a liquid-crystaldisplay device such as a vertical aligned (VA) liquid-crystal displaydevice.

2. Description of the Related Art

To form a liquid-crystal display device exhibiting excellent displayquality in all azimuths by compensation for birefringence of aliquid-crystal cell achieving display through a polarizer, the polarizerneeds to be combined with a phase retarder in which main refractiveindices nx, ny and nz in three directions, that is, two in-planedirections x and y in association an obliquely viewing direction and onenormal direction z, are controlled. Particularly in a VA or OCBliquid-crystal display device, the polarizer needs to be combined with aphase retarder in which the main refractive indices in the threedirections satisfy the relation nx>ny>nz.

As the phase retarder with controlled nx, ny and nz used in combinationwith the polarizer, there is heretofore known a phase retarder made fromuniaxially stretched films laminated so that in-plane slow axisdirections are perpendicular to each other or a monolayer phase retarderformed from a high-molecular film laterally or biaxially stretched by atenter. Each of these phase retarders is bonded to a polarizer having atransparent protective layer such as a triacetyl cellulose film throughan adhesive layer to thereby form an object.

Use of the former phase retarder, however, brings about a problem thatthe volume of the phase retarder is large because of use of tworetardation films. On the other hand, the range of retardation valueobtained in the latter monolayer phase retarder is narrow. In the casewhere the latter monolayer phase retarder is used and retardation valuein the direction of the thickness of the phase retarder is remarkablylarger than that in the normal direction, two or more phase retardersneed to be laminated in the same manner as the former phase retarder inorder to obtain the required retardation value. There arises still theproblem that the volume of the phase retarder is large.

SUMMARY OF THE INVENTION

An object of the invention is to provide a phase retarder-containingpolarizer which is excellent in reduction in thickness and which can beused for forming a liquid-crystal display device such as a VAliquid-crystal display device improved in viewing angle characteristicand high in contrast.

According to the invention, there is provided a wide viewing anglepolarizer having: a polarizing film; and a phase retarder adhesivelylaminated on at least one surface of the polarizing film through anadhesive layer, the phase retarder being made of a composite phaseretarder constituted by a laminate in which a retardation layer B of acholesteric liquid crystal-oriented solidified layer in a selectivereflection wavelength range of not larger than 350 nm is supported by aretardation layer A of a thermoplastic resin exhibiting positivebirefringence, the composite phase retarder being formed so that thelaminate has Re of not smaller than 10 nm and Rth−Re of not smaller than50 nm on the basis of light at a wavelength of 590 nm when Re and Rthare defined as Re=(nx−ny)X d and Rth=(nx−nz)X d respectively in which nxand ny are in-plane main refractive indices, nz is a thicknesswiserefractive index, and d is a layer thickness. There is also provided aliquid-crystal display device having: a liquid-crystal cell; and a wideviewing angle polarizer defined above and disposed on at least onesurface of the liquid-crystal cell.

According to the invention, the retardation layer B is excellent inreduction in thickness because it is made of a liquid-crystal coatingfilm. Moreover, because the retardation layer B is supported by theretardation layer A, a high-quality composite phase retarder excellentin reduction in thickness can be obtained. Moreover, because thecomposite phase retarder is bonded to a polarizing film so as to serveas a transparent protective layer, a separate transparent protectivelayer to be bonded to the polarizing film can be omitted. Hence, greaterreduction in thickness can be achieved. When the combination of thecomposite phase retarder and the polarizing film is used, the viewingangle of the liquid-crystal cell can be improved extremely.

Features and advantages of the invention will be evident from thefollowing detailed description of the preferred embodiments described inconjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWING

In the accompanying drawings:

FIG. 1 is a sectional view for explaining an embodiment;

FIG. 2 is a sectional view for explaining another embodiment;

FIG. 3 is a sectional view for explaining a further embodiment; and

FIG. 4 is a sectional view for explaining a still further embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The wide viewing angle polarizer according to the invention has: apolarizing film; and a phase retarder adhesively laminated on at leastone surface of the polarizing film through an adhesive layer. The phaseretarder is made of a composite phase retarder constituted by a laminatein which a retardation layer B (second retardation layer) of acholesteric liquid crystal-oriented solidified layer in a selectivereflection wavelength range of not larger than 350 nm is supported by aretardation layer A (first retardation layer) of a thermoplastic resinexhibiting positive birefringence. The composite phase retarder isformed so that the laminate has Re of not smaller than 10 nm and Rth−Reof not smaller than 50 nm on the basis of light at a wavelength of 590nm when Re and Rth are defined as Re=(nx−ny)X d and Rth=(nx−nz)X drespectively in which nx and ny are in-plane main refractive indices, nzis a thicknesswise refractive index, and d is a layer thickness.Hereupon, nx is an in-plane refractive index in the direction in whichthe in-plane refractive index becomes maximum within the plane of theplate, and ny is an in-plane refractive index in the directionorthogonal to the direction of nx.

Examples of the wide viewing angle polarizer 11 are shown in FIGS. 1 to4. In FIGS. 1 to 4, the reference numeral 3 designates a polarizingfilm; 4, an adhesive layer; 5, a retardation layer A; and 7, aretardation layer B. Incidentally, the reference numeral 1 designates atransparent protective layer; 2 and 6, adhesive layers; and 8, anoriented film.

The retardation layer A, which is one of constituent members of thecomposite phase retarder 10, is made of a thermoplastic resin exhibitingpositive birefringence. That is, the retardation layer A is made of athermoplastic resin exhibiting characteristic of na>nb in which na is arefractive index in a stretching direction and nb is a refractive indexin an in-plane direction perpendicular to the stretching direction whena film of the resin is stretched uniaxially.

The thermoplastic resin is not particularly limited. Any suitabletransparent resin exhibiting positive birefringence can be used as thethermoplastic resin. Examples of the thermoplastic resin includepolycarbonate, polyallylate, polysulfone, polyolefin, polyethyleneterephthalate, polyethylene naphthalate, norbornene-based polymer,cellulose-based polymer, and mixture polymer of two or three or morekinds of polymers selected from the aforementioned polymers.Particularly, a resin excellent in birefringence controllability,transparency and heat resistance is used preferably.

The retardation layer A can be formed in such a manner that a film ofthe thermoplastic resin produced by a suitable method such as anextrusion molding method or a cast film-forming method is stretched by amethod such as a vertical stretching method using a roll or a lateral orbiaxial stretching method using a tenter. The stretching temperature ispreferably selected to be near the glass transition temperature (Tg) ofthe film as a subject of treatment. Particularly, the stretchingtemperature is preferably selected to be not lower than Tg and lowerthan the melting point of the film.

In the vertical stretching method using a roll, there can be used asuitable heating method such as a method using a heating roll, a methodof heating an atmosphere or a method using the aforementioned methods incombination. In the biaxial stretching method using a tenter, there canbe used a suitable method such as a simultaneous biaxial stretchingmethod using a whole tenter technique or a sequential biaxial stretchingmethod using a roll-tenter technique. A layer little in variation inorientation and retardation is preferably used as the retardation layerA. The thickness of the retardation layer A can be decided suitably inaccordance with retardation or the like. Generally, from the point ofview of reduction in thickness, the thickness of the retardation layer Ais selected to be in a range of from 1 to 300 μm, particularly in arange of from 10 to 200 μm, more particularly in a range of from 20 to150 μm.

On the other hand, the retardation layer B, which is one of constituentmembers of the composite phase retarder, is formed as a solidified layerobtained in such a manner that cholesteric liquid crystal in a selectivereflection wavelength range of not larger than 350 nm is oriented andthen the oriented state is fixed. The thickness of the retardation layerB can be also decided suitably in accordance with retardation or thelike. Generally, from the point of view of reduction in thickness, thethickness of the retardation layer B is selected to be not larger than20 μm, particularly in a range of from 0.1 to 15 μm, more particularlyin a range of from 0.5 to 10 μm.

The cholesteric liquid crystal in a selective reflection wavelengthrange of not larger than 350 nm is used for achieving bright display bynot selectively reflecting light in a visible region but transmittingthe light. That is, the cholesteric liquid crystal exhibitscharacteristic of selectively reflecting part of light at wavelengthsnear the central wavelength of incident light at a wavelength nc·Pparallel to a spiral axis, as one of left- and right-hand circularlypolarized light components when nc is the average refractive index and Pis the spiral pitch on the basis of the spiral oriented state of thecholesteric liquid crystal. If the selective reflected light regionappears in the visible region, the quantity of light allowed to be usedfor display is reduced disadvantageously. Therefore, the cholestericliquid crystal is provided for preventing the quantity of light frombeing reduced.

As the cholesteric liquid crystal, there can be used a suitable oneexhibiting the aforementioned selective reflecting characteristic asdescribed in Unexamined Japanese Patent Publications No. Hei. 3-67219,3-140921, 5-61039, 6-186534 and 9-133810, etc. From the point of view ofstability of the oriented solidified layer, there can be preferably useda liquid-crystal material capable of forming a cholestericliquid-crystal layer, such as a cholesteric liquid-crystal polymer, achiral agent-containing nematic liquid-crystal polymer or a compoundcapable of forming the aforementioned liquid-crystal polymer bypolymerization with light, heat or the like.

For example, the retardation layer B can be formed in such a manner thata support base material is coated with cholesteric liquid crystal. Inthis case, a method of wet-on-wet coating the support base material withone kind or different kinds of cholesteric liquid crystal may be used inaccordance with necessity in order to control retardation. As thecoating method, there can be used a suitable method such as a gravurecoating method, a die coating method or a dipping method. Theretardation layer A or any other suitable polymer film may be used asthe support base material.

For the formation of the retardation layer B, a method for orientingliquid crystal may be used. The orienting method is not particularlylimited. Any suitable method that can orient a liquid-crystal compoundcan be used. Incidentally, an example of the method is a method oforienting liquid crystal with which an oriented film is coated. Examplesof the oriented film include: a rubbing-treated film of an organiccompound such as a polymer; a rhombic vapor-deposited film of aninorganic compound; a film having a micro-groove; and a film obtained byaccumulation of an LB film formed from an organic compound such asdioctadecyl methyl ammonium chloride or methyl stearate by theLangmuir-Blodgett technique.

Further, an oriented film capable of generating an orienting functionwhen irradiated with light maybe used. On the other hand, a method oforienting liquid crystal with which a stretched film is coated(Unexamined Japanese Patent Publication No. Hei. 3-9325) or a method oforienting liquid crystal under application of an electric field, amagnetic field or the like may be used. Incidentally, it is preferablethat the oriented state of liquid crystal is as uniform as possible. Itis also preferable that liquid crystal is provided as a solidified layerin which the oriented state is fixed.

The composite phase retarder is formed in such a manner that theretardation layer B is supported by the retardation layer A in order toachieve reduction in thickness. For example, as shown in FIGS. 1 and 2,the composite phase retarder is formed by a method in which a coatingliquid layer or a coating film provided on a support base material toform the retardation layer B 7 is transferred and bonded onto theretardation layer A 5 through an adhesive layer 6 as occasion demands.For example, the transfer can be performed by a method including thesteps of: forming the retardation layer B on a releasant-treated surfaceprovided on the support base material; providing an adhesive layer onthe retardation layer B as occasion demands; laminating the retardationlayer A on the retardation layer B; and separating the support basematerial through the releasant-treated surface.

On the other hand, as shown in FIGS. 3 and 4, the composite phaseretarder in which the retardation layer B is supported by theretardation layer A can be also formed by a method including the stepsof: providing the oriented film such as a rubbing film 8 on a surface ofthe retardation layer A 5 serving as one of constituent members of thecomposite phase retarder, as occasion demands; and orienting and fixinga cholesteric liquid-crystal layer on the oriented film. This method isparticularly preferred from the point of view of reduction in thickness.

The composite phase retarder is formed as a laminate exhibitingretardation characteristic in which Re is not smaller than 10 nm,particularly in a range of from 20 to 1000 nm, more particularly in arange of from 25 to 500 nm and Rth−Re is not smaller than 50 nm,particularly in a range of from 70 to 1500 nm, more particularly in arange of from 100 to 800 nm, on the basis of light at a wavelength of590 nm (this condition applies hereunder) when Re and Rth are defined asRe=(nx−ny)X d and Rth=(nx−nz)X d in which nx and ny are in-plane mainrefractive indices (in directions of slow and fast axes), nz is athicknesswise refractive index, and d is a layer thickness.

The provision of the composite phase retarder exhibiting the retardationcharacteristic can compensate for birefringence of any kind ofliquid-crystal cell such as a VA liquid-crystal cell or an OCBliquid-crystal cell and can be used for forming a liquid-crystal displaydevice excellent in viewing angle and contrast. For example, thecomposite phase retarder exhibiting the retardation characteristic canbe obtained by a method using the retardation layer A having Re of 20 to300 nm and Rh/Re of 1.0 to 50 and the retardation layer B having Re of 0to 20 nm and Rh Rth of 30 to 500 nm.

The wide viewing angle polarizer can be formed in such a manner that thecomposite phase retarder is adhesively laminated on one or each ofopposite surfaces of the polarizing film 3 as shown in FIGS. 1 to 4. Asthe polarizing film, it is possible to use a suitable one in accordancewith the related art without any particular limitation. For example, itis possible to use a polarizing film produced by the steps of: adsorbinga dichroic substance constituted by iodine and/or a dichroic dye such asan azo dye, an anthraquinone dye or a tetrazine dye onto a film made ofa hydrophilic polymer such as polyvinyl alcohol, partially formalizedpolyvinyl alcohol or partially saponified ethylene-vinyl acetatecopolymer; and stretching and orienting the film. When the compositephase retarder is provided on only one surface of the polarizing film 3as shown in FIGS. 1 to 4, a transparent protective layer made of atransparent film or the like may be provided on the other surface of thepolarizing film 3 as occasion demands. A film excellent in isotropy suchas a triacetyl cellulose film can be preferably used as the transparentprotective layer.

The retardation layer adjacent to the polarizing film may be A or B asshown in FIGS. 1 to 4. The adhesive layer for bonding the compositephase retarder and the polarizing film to each other is provided toprevent the optical axis from being displaced and prevent an aliensubstance such as dust from entering. The adhesive agent for forming theadhesive layer is not particularly limited in kind. From the point ofview of preventing the optical characteristic of constituent membersfrom changing, it is preferable to use an adhesive agent not requiringany high-temperature process for curing and drying in a bondingtreatment or an adhesive agent not requiring any long-term curing anddrying process. From this point of view, a hydrophilic polymer-basedadhesive agent or a pressure sensitive adhesive layer may be preferablyused.

Incidentally, for the formation of the pressure sensitive adhesivelayer, it is possible to use a transparent pressure sensitive adhesiveagent using a suitable polymer such as acrylic-based polymer,silicone-based polymer, polyester, polyurethane, polyether or syntheticrubber. Particularly, an acrylic-based pressure sensitive adhesive agentis preferred from the point of view of optical transparency, pressuresensitive adhesion, weather resistance, and so on.

Incidentally, the pressure sensitive adhesive layer may be provided onone or each of opposite surfaces of the wide viewing angle polarizer asoccasion demands in order to bond the wide viewing angle polarizer to asubject such as a liquid-crystal cell. In this cases if the pressuresensitive adhesive layer is exposed, the pressure sensitive adhesivelayer is preferably temporarily covered with a separator or the like sothat a surface of the pressure sensitive adhesive layer can be preventedfrom being contaminated with an alien substance before the pressuresensitive adhesive layer is put into practical use.

The wide viewing angle polarizer may be formed to have at least onesuitable functional layer on one or each of its opposite surfaces.Examples of the functional layer include: a protective layer similar tothe transparent protective layer for various kinds of purposes such aswater resistance; and an anti-reflection layer or/and an anti-glarelayer for the purpose of preventing surface reflection or the like. Theanti-reflection layer can be formed suitably as a light-coherent filmsuch as a fluorine-based polymer coat layer or a multilayermetal-deposited film. The anti-glare layer can be also formed as a resincoating layer containing fine particles or by a suitable method in whicha fine prismatic structure is provided on a surface by a suitable methodsuch as embossing, sandblasting or etching to thereby diffusesurface-reflected light.

Incidentally, examples of the fine particles include inorganic fineparticles and organic fine particles with a mean particle size of from0.5 to 20 μm. The inorganic fine particles are made of silica, calciumoxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmiumoxide, antimony oxide, etc. and may be electrically conductive. Theorganic fine particles are crosslinked or non-crosslinked fine particlesmade of suitable polymers such as polymethyl methacrylate andpolyurethane. One member or a combination of two or more memberssuitably selected from the inorganic fine particles and the organic fineparticles may be used as the fine particles. Incidentally, the adhesivelayer or pressure sensitive adhesive layer may contain such fineparticles so as to exhibit light-diffusing characteristic.

The wide viewing angle polarizer according to the invention can be usedfor suitable purposes such as formation of a liquid-crystal displaydevice 12. Particularly, the wide viewing angle polarizer can bepreferably used for optical compensation of a liquid-crystal cell 9. Theliquid-crystal display device can be formed by arrangement of the wideviewing angle polarizer on one or each of opposite surfaces of theliquid-crystal cell. In this case, either of the composite phaseretarder and the polarizing film may be disposed on the liquid-crystalcell side. Incidentally, for the formation of the liquid-crystal displaydevice, suitable optical elements such as a light-diffusing plate, abacklight unit, a light-condensing sheet or a reflecting plate may bedisposed as occasion demands.

EXAMPLE 1

A polyester film (PET) was vertically stretched through a heating rollto thereby obtain a retardation layer A having Re of 40 nm, Rth of 41 nmand a thickness of 60 μm.

On the other hand, a nematic liquid-crystal compound represented by theaforementioned formula and a chiral agent represented by the followingformula were mixed with each other to set a selective reflectionwavelength to be in a range of from 290 to 310 nm. A cholestericliquid-crystal solution obtained by adding a photo-polymerizationinitiator to the mixture was applied on a biaxially stretched PET film,heated at 80° C. for 3 minutes and then crosslinked by irradiation withultraviolet rays to thereby obtain a retardation layer B having athickness of 1.9 μm, Re of 2 nm and Rth of 132 nm. The retardation layerB was laminated on the retardation layer A through an acrylic-basedpressure sensitive adhesive layer having a thickness of 15 μm. Thebiaxially stretched PET film was separated to thereby obtain a compositephase retarder having Re of 42 nm and Rth of 173 nm.

Then, a polyvinyl alcohol film 80 μm thick was stretched by five timesin an iodine aqueous solution to thereby obtain a polarizing film. Atriacetyl cellulose film 80 μm thick was bonded to one surface of thepolarizing film through an acrylic-based pressure sensitive adhesivelayer. The composite phase retarder was bonded to the other surface ofthe polarizing film through a pressure sensitive adhesive layer so thatthe retardation layer A faced inward. Thus, a wide viewing anglepolarizer having a total thickness of 210 μm was obtained.

EXAMPLE 2

A wide viewing angle polarizer was obtained in the same manner as inExample 1 except that the composite phase retarder with the retardationlayers A and B inverted to each other in location was disposed so thatthe retardation layer B faced inward.

EXAMPLE 3

A composite phase retarder having Re of 41 nm and Rth of 173 nm and awide viewing angle polarizer having a total thickness of 231 μm wereobtained in the same manner as in Example 1 except that the retardationlayer A was made of a norbornene resin film laterally stretched by atenter and having Re of 40 nm, Rth of 102 nm and a thickness of 85 μmwhereas the retardation layer B was formed to have a thickness of 1.0μm, Re of 1 nm and Rth of 71 nm.

EXAMPLE 4

A wide viewing angle polarizer was obtained in the same manner as inExample 3 except that the composite phase retarder with the retardationlayers A and B inverted to each other in location was disposed so thatthe retardation layer B faced inward.

EXAMPLE 5

A triacetyl cellulose film was laterally stretched by a tenter tothereby obtain a retardation layer A having Re of 38 nm, Rth of 65 nmand a thickness of 49 μm. A solution containing 1% by weight ofpolyvinyl alcohol was applied on the retardation layer A and dried at90° C. to thereby form a coating film about 0.01 μm thick. A surface ofthe coating film was rubbing-treated to form an oriented film. Then, acholesteric liquid-crystal solution the same as in Example 1 was appliedon the oriented film, heated at 90° C. for 1 minute and crosslinked byirradiation with ultraviolet rays to form a retardation layer B having athickness of 1.5 μm, Re of 2 nm and Rth of 106 nm. In this manner, acomposite phase retarder having Re of 40 nm and Rth of 171 nm wasobtained. A wide viewing angle polarizer having a total thickness of 166μm was obtained in the same manner as in Example 1 except that thecomposite phase retarder obtained thus was used. Incidentally, thetriacetyl cellulose film was bonded through a polyvinyl alcohol adhesivelayer 5 μm thick.

EXAMPLE 6

A wide viewing angle polarizer was obtained in the same manner as inExample 5 except that the composite phase retarder with the retardationlayers A and B inverted to each other in location was disposed so thatthe retardation layer B faced inward.

Comparative Example

A polarizer obtained by bonding triacetyl cellulose films onto oppositesurfaces of a polarizing film obtained in Example 1 was used singly.

Evaluation Test

(Wide viewing angle) polarizers obtained in each of Examples andComparative Example were disposed on opposite surfaces of a VAliquid-crystal cell in the form of crossed-Nicol to thereby obtain aliquid-crystal display device. A viewing angle exhibiting contrast ofnot lower than 10 was measured in each of an up-and-down direction, aleft-and-right direction, a direction of diagonal 1 (45° and −225°) anda direction of diagonal 2 (135° and 315°). Incidentally, the compositephase retarder was disposed on the cell side in Examples 1 and 2 whereasthe polarizing film was disposed on the cell side in the other Examples.

Results of the measurement were as shown in Table.

Viewing Angle Up-Down Left-Right Diagonal 1 Diagonal 2 Example 1 x80 x80x65 x65 Example 2 x80 x80 x65 x65 Example 3 x80 x80 x60 x60 Example 4x80 x80 x60 x60 Example 5 x80 x80 x65 x65 Example 6 x80 x80 x65 x65Comparative x40 x40 x30 x30 Example

It is obvious from Table that the viewing angle exhibiting high contrastis widened in Examples. It is obvious from the above description that awide viewing angle polarizer which can be used for forming aliquid-crystal display device thin in thickness, light in weight,excellent in productivity and visibility and high in display quantity isobtained according to the invention.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form can be changed in the details ofconstruction and in the combination and arrangement of parts withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

1. A wide viewing angle polarizer comprising: a polarizing film; and aphase retarder adhesively laminated on at least one surface of saidpolarizing film through an adhesive layer, said phase retarder beingmade of a composite phase retarder constituted by a first retardationlayer and a second retardation layer, which is a laminate in which a thesecond retardation layer of a cholesteric liquid crystal-orientedsolidified layer in a selective reflection wavelength range of notlarger than 350 nm is supported by a the first retardation layer of athermoplastic resin exhibiting positive birefringence, said compositephase retarder being formed so that said laminate has Re of not smallerthan 10 nm and Rth−Re of not smaller than 50 nm on the basis of light ata wavelength of 590 nm when Re and Rth are defined as Re=(nx−ny)X d andRth=(nx−nz)X d respectively in which nx and ny are in-plane mainrefractive indices, nz is a thicknesswise refractive index, and d is alayer thickness.
 2. A wide viewing angle polarizer according to claim 1,wherein said first retardation layer in said composite phase retarderhas Re of 20 to 300 nm and Rth/Re of not smaller than 1.0 whereas saidsecond retardation layer in said composite phase retarder has Re of 0 to20 nm and Rth/Re of 30 to 500 nm.
 3. A wide viewing angle polarizeraccording to claim 1, wherein a pressure sensitive adhesive layer isprovided on at least one of opposite surfaces of said wide viewing anglepolarizer.
 4. A liquid-crystal display device comprising: aliquid-crystal cell; and a wide viewing angle polarizer according toclaim 1 and disposed on at least one surface of said liquid-crystalcell.